1. Field of the Invention
The invention pertains to the field of cutting oils.
Metal cutting and grinding have as their objective a progressive removal of metal from the work piece in the form of chips rather than by plastic reforming of the metal. In the field of metal cutting, the use of single and multiple point tools is well known and a great deal of metal working lubricant is used in the metal cutting process. In general, two types of lubricants are needed; a metal cutting lubricant and a machine oil. The cutting oil serves to remove heat generated during machining of the metal and lubricates the cutting tool against the work and chips. The machine oil lubricates the machine parts.
Cutting oils are generally paraffinic or intermediate base mineral oils. These are preferred because such products generally create less fog or smoke than naphthene oil. In severe conditions, which are more normal than not in heavy duty operations, it may be necessary to use an additive package in the cutting oil. This package will comprise extreme pressure additives cooper corrosion inhibitors, oxidation inhibitors, anti-mist agents, odorants to mask or remove the odors of other additives and other additives for special situations.
It is desirable when considering cutting oils and machine lubricants to think in terms of using one oil for both purposes. The use of a single oil rather than two or more has many advantages including reduced lubricant stock inventory and removal of the effects of cross-contamination of cutting oil and machine lubricant. Although dual purpose cutting oil formulations have been used in automatic screw machines for several years, these formulations often cannot be used in heavy duty cutting operations. Conversely, it is known that heavy duty cutting oil cannot normally be used as machine lubricants since in general they are unsatisfactory in copper corrosion characteristics.
2. Statement of the Prior Art
The prior art to which this invention relates is aware; inter alia, of the following patents: U.S. Pat. Nos. 3,459,663; 3,816,311; 3,853,638.
A more relevant patent is coassigned U.S. Pat. No. 3,929,652 which discloses a dual purpose oil comprising a major amount of a base oil and minor amounts of Bis(B-chlorophenethyl) disulfide and of an alkyl derivative of 2,5-di-mercapto-1,3,4-thiadizole. The compositions of the present invention constitute an improvement over the aforesaid oil in providing superior performance in severe machining operations and not requiring an odor masking agent.